The large variety of components utilized in different kinds of vaccines make it difficult to summarize all the ways in which light scattering are applied to vaccine development. Here are a few:
Polysaccharides tend to be very heterogeneous; properties of interest include distributions of molar mass and size as well as conformation. In most instances SEC-MALS combined with online DLS provides good resolution and complete information. When the polysaccharide molar masses are very high and the molecules highly branched, FFF-MALS-DLS will provide better data since the 'anchoring' effect causing anomalous SEC separation does not occur in FFF.
SEC column calibration cannot be used for characterizing the molecular weights of protein-polysaccharide conjugates, because relevant standards do not exist. Only SEC-MALS employing the triple-detector technique (UV-MALS-RI) and 'Conjugate Analysis' algorithms provides accurate and reliable analysis of molar masses, providing not only the total molecular weight but also the masses of the constituent protein and polysaccharide. Even if an additional component such as lipid is incorporated into the complex, it is possible to determine protein and total molar masses.
The same analysis may be applied to FFF separations.
Viruses and virus-like particles (VLP)
Light scattering coupled to FFF is one of the more convenient methods for determining virus particle counts, with results very similar to those of cryo-TEM.
DLS, SEC-MALS and FFF-MALS are used extensively in the course of developing and producing VLPs:
- SEC-MALS for assessing assembly of capsomeres into well-formed VPS as well as VLP molecular weight, size, aggregation state, shape and even payload
- FFF-MALS for the same characterizations when VLPs do not elute well from SEC columns
- DLS for high-throughput formulation
Lipsosomes may be used as adjuvants as well as delivery vehicles for antigens. DLS is an excellent means of rapidly assessing liposome size. When more accurate distributions are needed or additional characterization such as shape or payload, SEC-MALS and FFF-MALS provide reliable results with excellent resolution.
Need to assess the degree antibody binding to an isolated antigen protein or a complex vaccine such as a VLP? CG-MALS determines binding affinity and absolute molecular stoichiometry, in solution, without labeling. It is also invaluable in assessing protein-protein interactions in multi-valent vaccines that include more than one antigen.